Sheet metal blade base



Jan. 14, 1958 o. A. WAYNE 2,319,870

SHEET METAL BLADE BASE' Filed April 18, 1955 1N VENTOR ATTORNEYS United States Patent SHEET METAL BLADE BASE Oleh A. Wayne, Cleveland, Ohio Application April 18, 1955, Serial No. 502,260

Claims. (Cl. 253-77) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the'United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to turbine blade bases.

In turbines it is usual to make the blade separately and aflix the blade root to the turbine wheel run by some convenient mode of attachment such as interlocking ridges and grooves extending laterally of the wheel rim. Heretofore, in general, the blade base has been cast with no internal openings except for air cooling and blade attachment, so that the rim loading has been pronounced. Generally stated, the present invention contemplates utilization of sheet metal stampings in a novel arrangement as a substitute for the usual casting.

An outstanding object of the invention is to provide a blade base for turbines which will permit substantial reduction in the Wheel rim loading. Objects also are to provide a blade base which will permit important reductions in turbine material and time of fabrication of the blade bases.

Other objects and features of the invention will become apparent on consideration of the following detailed description of the base construction and of the accompanying drawings, in which Fig. l is a perspective view of the assembled blade base;

Fig. 2 is an exploded view, in perspective, of the various component base parts; and

Fig. 3 is a sectional view of the blade base taken along lines 3--3 of Fig. 1.

The blade base is formed of three component parts, the outer shell 11, the inner shell 12 and the base plate 13, these parts being formed for telescopic engagement. The outer shell 11 is broadly U-shaped with an elongated back plate 14 provided with a crescentic opening 15 extending axially and bounded by an outstanding edge rim 16. The side plates 17 and 18 of this shell are inturned and terminate in edge channels or grooves 19 adapted to engage corresponding ribs on the inner shell as will be more fully described hereinafter. The grooves 19 form corresponding ridge protuberances 20 on the outer sides of side plates 17 and 18, which are adapted to engage cooperative transverse corrugations in the wheel rim for rigid attachment thereto.

The inner shell 12, similarly, is U-shaped with an elongated back plate and side plates 26 and 27. The back plate 25 is apertured in approximate conformity to the outer shell opening 15 but with parts of the inner shell back plate 25 underlying the opening for blade support. In forming this shell a support flange or section 28, centrally placed along side 26, is cut in the back plate and bent upwardly and backwardly to form a support adapted to engage the back plate of the outer shell. Also, on the opposite side adjacent side plate 27, support tabs or sections 29 and 30 are cut for outward extension and contact against the adjoining outer shell back plate 14. Additionally, the back plate 25 is extended 2,819,870 Patented Jan, 14,

at both ends ,to form end plates 31 and 32 which are bendable at right angles downwardly to form end closures for the shell unit. The edge outline of these end plates conforms to the end boundaries of the outer shell 14 so that on bending they are received and enclosed by the outer shell edges, as shown in Fig. 1.

The side plates 26 and 27 of inner shell 12 are in wardly grooved in the free vedge sections adjacent the edges thereof to form support channels 34 for reception of base plate 13, the corresponding curved ridges 35 being adapted for cooperative sliding engagement with the grooves 19 of outer shell plates 17 and 18. As indicated, base plate 13 is elongated, corresponding in length to shell 11, and is preferably formed with rounded edges 40 to facilitate assembly in the unit. Openings 41 insure material reduction and permit air flow to the blades for cooling, if desired.

In assembly, the plate 13 is slid into the channels or grooves 34 of the inner shell walls 26 and 27 and the end sections 31 and 32 of the shell turned down to form end closures. This unit is then slid in the channels or grooves 19 of the outer shell walls 17 and 18 to form the complete base unit of Fig. 1. The shell material is elastically yieldable to a limited extent and due to this elasticity there is some blade yield in the plane of wheel rotation, thereby reducing the tendency of the blades to vibrate in the fundamental mode of the wheel, and thus reducing destructive blade vibration.

All metal parts are readily stamped and fabricated thus markedly reducing construction time over the older methods of casting and machining. The reduction in metal over prior blade bases is as high as 25% thus permitting reduction in rim loading and total wheel weight.

As shown in Fig. 3 the blade 50 rests at its root end on the flange 28 and inner shell base plate 25 and is attached to the edge rim 16. Furnace brazing, as in a hydrogen furnace, may be used for attachment. Flange 28 and tabs 29 and 30 are preferably brazed to the contacting outer shell areas so that relative movement between the shells is prevented.

Obviously, modifications of the described disclosure may be made; and it is therefore understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A turbine blade base for attaching turbine blades to turbine wheels provided with transverse rim slots comprising an outer shell, an inner shell fixed within said outer shell and a base plate enclosed within said inner shell, said inner shell being substantially U-shaped in cross section and having back and side plates, the free edge sections of said side plates being channeled for reception of said base plate and end plates attached to the ends of the back plate of said inner shell and projecting over the inner shell and base plate ends for restraining end movement of said base plate; and said outer shell being substantially U-shaped in cross section with back and side plates contoured and dimensioned to enclose snugly said inner shell and end plates and to fit into one of said rim slots, the back plate of said outer shell being apertured to receive the root end of a turbine blade; and means for attaching said blade root end to said outer shell.

2. The turbine blade base as defined in claim 1, and means for preventing relative movement between said shells.

3. The turbine blade base as defined in claim 2, with sections of said inner shell extending transversely to underlie the aperture formed in said outer shell and to form a base support for the blade root.

4. A turbine blade base for attaching turbine blades to turbine wheels provided with transverse rim slots comprising an outer shell, an inner shell fixed within said outer shell and a base plate enclosed within said inner shell, said inner shell being substantially U-shaped in cross section and having back and side plates, the free edge sections of said side plates being channeled for reception of said base plate and means mounted on the inner shell ends and forming a closure therefor for securing said base plate between the channeled sections of said inner shell side plates; and said outer shell being substantially U-shaped in cross section with back and side plates contoured and dimensioned to enclose snugly said inner shell and to fit into one of said rim slots; and means for attaching a wheel blade to the back plate of said outer shell.

S. The turbine blade base as defined in claim 4, with the side wall plates of said inner and outer shell being elastically yieldable whereby on wheel rotation blade vibration is reduced.

References Cited in the file of this patent UNITED STATES PATENTS 913,273 Emden Feb. 23, 1909 1,516,607 Iohanson Nov. 25, 1924 2,613,058 Atkinson Oct. 7, 1952 2,656,146 Sollinger Oct. 20, 1953 UNITED STATES PATENT ()FFICE CERTIFICATE OF CORRECTION Patent N00 2,819,870 January 14, 1958 Oleh A, Wayne It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 2, for "side Wall plates" read -===side plates,

Signed and sealed this 14th day of October 1958 (SEAL) Attest:

KARL H, .AXLINE ROBERT C. WATSON Atteeting Ofiicer Commissioner of Patents 

